Absorption refrigerating machine



it tented Apr. 8,

2,237,622 ABSORPTION REFRIGI iItATING MACHINE Earl F. Hubacker, Highland Park, Mich assignmto Borg-Warner Illinois Corporation, a corporation of 2 Application September 25, 1935, Serial No. 41,998

17 Claims. 2 (Cl. 62--5) This invention relates to refrigerating machines of the absorption type; that is, to machines in which heat is employed for separating out in a generator an evaporable fluid which is condensed and thereafter evaporated at a lower pressure in an evaporator and from whence the fluid passes through an absorber and is returned again to the generator by increasing the pressure of the fluid to a pressure slightly in excess of the generator pressure.

An object of the invention is to build a machine of this type particularly in relatively small sizes, although the machine is not in any way limited to small sizes, that will operate continuously and automatically with any source of heat and, that can be air-cooled. v

Another object of the inventionis to build an inexpensive machine of the above type by simplifying the elements thereof to such an extent as not to require many of the valves, pumps and controls heretofore found necessary in such machines.

Another object of the invention is to provide in such machines simple metering devices for transferring fluid between regions of different pressures and then for varying the amount of fluid transferred in accordance with the varying demand for refrigeration which is placed upon thesystern.\-.

Another object ofthe invention is to provide a heat pump mechanismx capable of operation by the source of heat employed for heating the fluid in the generator, the device being adaptedto operate upon a thermosiphon principle to force liquid into the generator. whenever the device is iilled with liquid by the absorber.

Another object 01 the invention is to provide a heat exchange device adapted to cool weak liquor withdrawn from the generator by employing-the circulating air=supplied to the generator.

Another object of the invention is to provide an improved absorber where the refrigerant in the system may be absorbed by the weak liquor therein andwherein a continuous condition 0 turbulent motion is maintained.

Another object of the invention is to provide a simplified structure and compactarrangement v of the elements employed in refrigerating systems of this type.

For a better understanding of the invention, reference may now be had to the accompanying drawings forming a part of this specification, in which:

Fig. 1 is a diagrammatical view of a refrigerating system embodying the principles of the invention;

Fig. 2 is a front view, partly in elevation and partly in cross-section, of a refrigerator suitable for household or domestic use and being equipped with the refrigerating system embracing the principles of the invention; and

Fig. 3 is a vertical sectional view of the lower part of the refrigerator illustrated by Fig. 2, taken substantially upon the line 3--3 of Fig. 2.

Referring particularly to the drawings, the numeral l0 illustrates generally a cabinet or box having an upper heat insulated refrigerating compartment i I and a lower apparatus compartment I2. The refrigerating compartment has an inner liner l3 surrounded by material I of good heat insulating quality. Both the heat insulated compartment and the apparatus compartment have a unitary outer shell IS. A frame I5 is provided throughout the structure for supporting and holding together the various elements embraced therein. A door I1 is adapted to provide a closure member for the insulated compartment H and likewise the apparatus compartment has a door I 8.

In the apparatus compartment, at one side of and near the rear of the latter, is disposed a generator I 9 consisting of an inner combustion chamber shell 20, an. outer shell 2|, and a flue 22 forming a passage through the upper part of the two. The two shells are welded together at the lower extremities thereof to provide a closed generating chamber 23 internally thereof.

A shell 24, providing an accumulating chamber or accumulator 25, is located above the stack 22 in such position that the products of combustion from the inner shell '20 pass outwardly through the stack for heating the accumulator. The

generator and the accumulator are connectedby a conduit 28 extending from the vapor space in the upper part of the generator to the liquid space in the lower part of the accumulator.

the generator.

Both the generator and the accumulator are surrounded by a heat insulating casing 3| having a stack or outlet 32 connected with a larger stack 33 extending entirely across the back of the cabinet III and downwardly behind the apparatus compartment I! in such position as to provide an outlet upwardly along the back of the cabinet, both from the heat insulated generator l9 and the space within the apparatus compartment l2 thereabout. The products of combustion from the generator is therefore are adapted to pass upwardly through the stack 22, around the accumulator 25, out through the stack 32, and then into the region above the cabinet through the larger stack 33,

The generator I9 can be supplied with any kind of heat, as, for example, by heat from the oil burner or lamp 34 projecting into the lower part of the shell 20.

The generator l9 may be filled with any suitable absorbent and refrigerating fluids, as, for example, ammonia and water, and when these fluids are heated by the operation of the burner 34, the ammonia vapor from the generator will pass into the accumulator through the conduit 28, will pass through the accumulated liquid contained therein, and thence to the vapor space in the upper part thereof above the upper end of the tube 29. Any accumulated particles of liquid from the generator I 9 will be collected in the liquid within the accumulator before the.

vapor passes into the vapor space thereabove.

From the top of the accumulator the ammonia vapor passes through an outlet conduit 38 into a rectifier 31, which is built either sloping or otherwise in such manner as to drain any water vapor condensed in the rectifier back into the accumulator 25. The rectifier, as illustrated, is simply a thin coil located somewhat above other parts of the apparatus in a region where it will be exposed to air already heated by other parts of the apparatus. This air, though, will be cool enough to sufliciently cool the rectifier to condense out the water vapor therein, inasmuch as the fluid in the rectifier is much hotter than the fluid in 40 other parts of the apparatus which has to be cooled. From the rectifier I1 relatively pure ammonia vapor flows through a conduit 38 to a condenser 39 located in a lower region of the apparatus compartment l2, where the condenser will be exposed to cooler air from beneath the cabinet l which will rise through the condenser, the rectifier 31, and thence will pass outwardly through the stack 33. The liquid ammonia condensed by the condenser 39 passes upwardly through a liquid conduit 4i and is forced through a capillary expansion tube 42 into the vapor expansion space within an evaporator 43.

The evaporator 43 is located in the upper part of the cooling compartment ll of the refrigerator and in such position as to cool the air therein by natural draft circulation. The evaporator 43 also is provided with shelves 44 in which ice trays can be located for freezing water into ice cubes, etc.

The conduit 4| passes from the apparatus compartment l2 to the refrigerating compartment ll through a groove 48 formed in the door opening adjacent the front edge of the compartment in such manner that the evaporator 43 and the apparatus within the apparatus compartment II can be entirely removed from the cabinet I. without disconnecting anything. The entire apparatus therefore can be welded into a single unit and inserted and removed from the cabinet without disconnecting any of the parts thereof.

The capillary tube or metering device 42 consists of a relatively small tube such as that indicated at 41, which is helically wound within a largertube or casing 48 which can be welded between various parts of the apparatus where 9.

metering device is required. The tube 41 provideiuthe only passage through the tube or casing When the liquid ammonia from the liquid line 4i is expanded and reduced in pressure by the metering device or capillary tube 41, it immediately reduces the temperature of the evaporator 43 by evaporation therein and provides ammonia vapor therein as a result of the heat absorbed from the evaporator and the cabinet. The ammonia vapor thus formed passes from the evaporator through a vapor conduit 4! positioned within the groove 44 alongside of the liquid line 4| and the opposite end of which is connected to the lower end of an absorber 5i located within the apparatus compartment I2 somewhat above the condenser 39. Also attached to the lower end of the absorber ii is a metering device If, adapted to discharge weak liquor from the gen- 2 erator i9 into the absorber from the end of a weak liquor conduit 53. The opposite end of the conduit 53 is provided with a spirally wound section indicated at 64, which is located between a spaced pair of baiiles i and 61 and the inner edges of which contact with the lamp 34 and the lower edge of the generator I! respectively, in such manner as to provide a controlled inlet for the air supply required by the lamp. The opposite end of the spirally wound section I4 is connected to the lower part of the generator l9 as at 51a in such manner as to withdraw water or weak liquor from the generator wherefrom practically all of the liquid ammonia has been separated by vaporization. The weak liquor flowing from the generator through the section l4 will be cooled sufliciently by the air supplied to the burner between the baiiies i8 and I1 to be supplied to the absorber 5| through the metering device 52,

The absorber M is built of a long section of tubing, indicated at 54, which slopes upwardly away from the inlet from the conduit 4! and the weak liquid supply line 53. This tubing is.covered with fins 58 disposed in spaced relation thereon to increase the heat exchange surface thereof. Weak liquor from the weak liquor supply and discharged through the metering device 52 will practically fill the tube II. This liquid will be continuously agitated by additional liquid supplied through the metering device 52 and by the ammonia vapor exhausted thereinto from the conduit 46 which is continuously absorbed by the weak liquor. As ammonia vapor flows from the evaporator 43 into the absorber i I, 55 the pressure in the absorber will be lower than that in the evaporator. As this absorption process continues, the upper end of the tube 54 will be progressively filled with relatively strong liquor.

This liquid will overflow through absorber outlet 6|, check valve .2, and inlet tube 83, into the upper part of heat pump apparatus or generatorabsorber 64. This apparatus comprises a. casing or receiver 66 having a metering device 81 connected to the upper portion thereof for discharg-v ing weak liquor thereinto from a second weak liquor supply conduit 89. The latter conduit also has a spirally formed section 1| which is nested within the spirally formed section 54 of the weak liquor supply conduit 53 and is connected to the vapor contained therein, whereby the pressure within the casing will be reduced to a value lower than the pressure within the absorber 8i and in which event liquid will flow from the absorber to the casing until the latter is substantially filled.

The casing 68 also has an automatic siphon l4 attached thereto, with one end of the siphon attached to the bottom of the casing and the other to the top thereof. The end attached to the bottom has an upwardly projecting loop I8 formed therein, and the upper end of whichis positioned about where it is desired that the liquid level within the casing 68 should be limited. The opposite end of this loop connects with an upwardly inclined bend or heating unit 11 which projects through an opening I8 formed in the side of the generator IS in such position that the bend can be inserted within the generator above the lamp. The opposite end or the bend communicates with the upper end of the casing 88 through a connecting section 18. when the pressure in the casing 66 is reduced to such an extent as to cause a surge of liquid from the absorber ii, the casing will be illled quickly to or above the level of the upper end of the bend 18. When liquid finally flows over the bend into the heating section 11, a siphon will be formed in the bend 16 which will continuously discharge liquid irom the casing 66 to the heating section 11. As soon as any liquid flows into the heating section 11 above the lamp 34, some of the ammonia in the liquid will immediately vaporize and flow upwardly through the connecting section 11 into the upper part oi the casing Ii. This upward passage of vapor through the section 13 will at once lift the liquid in the section over the upper end thereof, and this, together with the siphon eflect produced by the bend I8, will cause a continuous circulation of liquid from the lower part of the casing 66 to the upper part thereof. As this liquid circulates through the loop 11, more of the ammonia will be evaporated irom the liquid therein until finally the pressure within the casing 88 caused by this vaporization of ammonia will exceed the pressure within the generator l8. When this condition is reached, substantially all oi the liquid within the casing 68 will be discharged through conduit 8! and coil 82 into the accumulator 25. As the liquid level within the casing 66 falls below the lower extremity of the bend l'l, there will be an unbalanced hydrostatic head within the siphon l8, and this will cause a reverse flow of liquid through the siphon from the bend l1 and into the casing 88, thereby emptying the siphon and the heating section 11 as the remainder of the liquid is forced from the casing 68 into the accumulator.

The end of the conduit 8| providing anoutlet for the casing 66 is connected to the lower end of the casing with the end thereof projecting within the casing in such a way as to retain within the casing a small amount of liquid. This liquid is the liquid that is drained from the heating section I'l during the latter part oi the how from the casing 68 and consequently is practically a weak liquor as a result of the boiling of ammonia therefrom in the heating section 11. This small amount of weak liquor in the bottom of the easing 36 will tend immediately to absorb some ot the high pressure gas within the casing 88 to reduce the pressure within the casing to provide a difference in pressure between the generator I! and the casing so that liquid will flow through the metering device 81.

A check valve 84, located in the conduit Ill, prevents the return flow of liquid from the conduit to the casing 66 after the discharge of the latter is completed and thus will permit a reduction in temperature and pressure within the casing 66 as a result of the weak liquor retained in the bottom of the casing and not discharged to the accumulator by absorption of the high temperature and high pressure ammonia vapor therein. Inasmuch as there is only a small quantity of ammonia vapor to be absorbed, since no further vaporization of ammonia takes place after the coil 11 is emptied, the temperature and pressure ofthe casing 86 will be very quickly reduced to such an extent that a further charge of strong liquor will soon flow into the casing from the absorber, thus filling the casing and automatically repeating the cycle of operation previously described.

If it is desired to increase the time required for absorbing the ammonia within the casing 66, this may be done by adding fins to the exterior surface ofthe casing 66. These fins will rapidly reduce the temperature of the casing, and consequently some of the ammonia vapor in the casing will be condensed into liquid ammonia during the time that vaporous ammonia is being absorbed by the weak liquor introduced into the casing for the purpose of absorbing such ammonia vapor.

After the discharge of the casing 66 is completed, the coil 82 and part of the conduit 8| down to the check valve 84 will remain substantially filled with a rich liquor'of ammonia and water, and this will be heated in the coil to a temperature substantially equal to the temperature maintained within the accumulator 25. The size of this coil can be apportioned in such a way as to hold practically all of the liquid discharged from the casing 66 by a single operation of the latter to the end that a new cold charge of rich liquor item the casing 86 will simply displace the previous charge contained within the coil 82. In

this way a substantial reduction in the temperature and pressure within the generator and the accumulator which might be caused by the discharge of an appreciable quantity of cold liquid thereinto can be prevented.

A baffle, indicated at 86, may be employed across the bottom of the apparatus compartment I 2, and this baille may be provided with suitable openings therein so as to direct the air circulating through the apparatus compartment in contact with the parts which it is desired to cool, thus preventing the flow around these parts of a large amount of cooler air which would adversely affect the draft across the apparatus by reducing the temperature that could be maintained' within the stack 33. The edges of this baiile may be secured to the frame l5 around the base of the apparatus compartment. A sloping baille also is employed above the apparatus for directing heated gases into the stack 33.

When once the burner 34 is lighted, the appanatus is adapted to operate as a continuous, nonmechanical ammonia and water absorption system. To control and regulate the amount of retrigeration performed by the system, a suitable pressure actuated valve or control 88 may be employedi'or the purpose of varying the amount of voil supplied from supply tank 89 to the lamp 34 through supply line 9|, thereby varying the amount of heat absorbed by the generator l9 and the amount of liquid ammonia condensed by the condenser and supplied to the evaporator. The greater the amount of heat supplied, the greater will be the amount of ammonia vapor delivered to the condenser by the generator. The surface of the condenser 39 being constant, it will be apparent that if a greater amount of ammonia vapor is delivered to the condenser, this ammonia vapor will have to be condensed at a relatively higher pressure, and under such circumstances this higher pressure will cause a greater amount of liquid to be delivered to the evaporator by the metering device 42. Not only this, but the rate of delivery of weak liquor by the metering devices 61 and 62 will be increased to increase correspondingly the amount of ammonia vapor absorbed in the absorber, and the rate at which the vapor pressure in the heat pump 64 will be reduced. When the demand for refrigeration upon the evaporator 43 is decreased, the amount of oil supplied to the burner 34 will be proportionally reduced by the operation of the aforesaid control and hence the amount of liquid supplied to the evaporator for vaporization purposes and of that supplied to the absorber and heat pump for absorption purposes will be correspondingly decreased. The control may be of the fluid actuated type having a bulb 92 applied directly to the evaporator, if desired, in such a position as to respond to the temperature of the shelves thereof and also may be positioned in such manner as to be affected by the circulating air wf him the compartment I I. Under such circ tances I the amount of ammonia supplied to the evaporator by the generator will be affected both by the demand for refrigeration upon the evaporator shelves and in the interior of the compartment It m'll be apparent that while the amount of heat supplied by the lamp 34 may vary, the generator, as long as the lamp may be burning at all, will always supply liquid ammonia to the evaporator 43 and weak liquor to the absorber 5| and the heat pump 64, thus providing a machine that is at all times continuous in operation. It will, of course, also be apparent that the machine may be cycled, if this is considered desirable, by turning down the lamp so that no appreciable amount of heat is delivered thereby.

During the continuous operation of the apparatus, the heat pump 64 will operate automatically to discharge at intervals the liquid contained within the casing 66 from the low primsure side of the apparatus or the absorption and evaporation side to the high side of the apparatus or the generating and condensing side. done simply by first absorbing the ammonia vapor from within the casing 66 to provide a pressure lower than the absorber pressure, then filling the casing 66 with liquid until the liquid therein overflows and siphons into the heating coil 11 where ammonia vapor is immediately and automatically vaporized to provide a pressure within the casing 66 high enough to force all of the liquid therein into the high pressure side of the apparatus or generator. When this movement of liquid is completed, no further pressure will be generated in the casing 66 because no liquid will then be contained within the loop 11. The gas in the loop 11 will, of course, be continuously heated by the lamp 34, but the heating of such gas will not vary the pressure within the casing 66. Instead of this, the vapor in the casing will be absorbed to reduce the pressure therein even though some of the vapor is still being heated within the loop 11.

While the metering device 61 is never shut 01f by any mechanical operation, the metering of fluid from the generator to the casing 66 nevertheless is discontinued except when the pressure This is the generator. When the pressure in the casing 66 is higher than that in the generator during periods when the'liquid is being discharged from r the casing 66, there is such a slight difference in pressure across the metering device 61 that very little, if any, fluid will flow through the metering device in the direction opposite that in which weak liquor is adapted to flow.

It is not intended that the invention should be limited to the exact structure illustrated herein, this being shown merely for the purpose of providing a practical embodiment of the invention on which the appended claims are drawn to cover any of the forms, applications, modifications and embodiments in which the invention may appear.

I claim:

1. A refrigeration apparatus comprising a generator, heating means for said generator, means for varying the supply of heat applied to said generator, an evaporator and an absorber, said heat supply varying means being associated with said evaporator and operable responsive to the thermal conditions therein, means for maintaining said generator and said evaporator and said absorber at different pressures and for continuously supplying variable quantities of liquid from said generator to said evaporator and said absorber respectively in proportion to the amount of heat supplied to said generator and means operable responsive to said heating means for effecting the transfer of strong liquor from said absorber to said generator.

2. An apparatus for refrigeration comprising an absorber having an upwardly inclined passage, means for continuously supplying vaporous ammonia to the lower extremity of said passage, and means for continuously supplying water to the lower extremity of said passage, thereby to create a continuous turbulence within the fluid within the casing 66 is lower than that within contained within said passage, the pressure in said absorber being maintained at a pressure lower than the pressure at the source of said vaporous ammonia.

3. An apparatus for refrigeration comprising a receiver and an absorber, said receiver being connected to said absorber for receiving strong liquor therefrom, a generator connected to said receiver and adapted to receive said strong liquor contained therein, and heat-exchanging means comprising a looped conduit having the opposite ends thereof attached to said receiver for increas the pressure within said receiver to a value greater than the pressure in said generator when.

said receiver is substantially filled with said strong liquor.

4. An apparatus for refrigeration comprising a receiver and a generator, said receiver being adapted to be filled with strong liquor to be discharged into said generator, a fluid heating element attached to said receiver for receiving some of the liquid therefrom when said receiver is substantially filled, and means for withdrawing liquid from within said heating element a the liquid level falls within said receiver.

5. An apparatus for refrigeration comprising a heating element continuously subjected to a heat source and a receiver, a liquid siphon attached to said receiver for filling said heating element with liquid from said receiver when the level of the liquid therein rises to a predetermined level, and discharge means for said receiver for discharging the contents of the latter after said heating element is filled with liquid.

6. An apparatus for refrigeration comprising a strong liquor receiver and a heating element, and a reversible siphon connecting said receiver and said heating element for filling said heating elea generator and an absorber having a receiver ment when said receiver is filled and for emptying said heating element when said receiver is being emptied.

7. An apparatus for refrigeration comprising a generator having a source of heat for heating the same and an air inlet for supplying air to said source of heat, conduit means ,lfor withdrawing weak liquor from said generator, said conduit means being positioned in said inlet to be cooled by said air supplied to said source of heat.

8. A method of refrigeration which comprises withdrawing strong liquor from an absorber to fill a strong liquor receiver and when said strong liquor receiver is substantially filled withdrawing some of said liquid from said receiver and evaporating the same for expelling said strong liquor from said receiver and supplying weak liquor to said receiver for absorbing the evaporator liquid therein.

9. A method of refrigeration which comprises withdrawing strong liquor from an absorber to fill a strong liquor receiver and when said strong liquor receiver is substantially filled withdrawing some of said strong liquor from said receiver and evaporating the same for expelling said strong liquor from said receiver and when said strong liquor receiver is substantially empty returning to said receiver any remainder of the liquid withdrawn therefrom which is not evaporated during said liquid-expelling process.

10. An apparatus for refrigeration comprising a generator and absorber having a strong liquor receiver connected therebetween, pressure increasing means associated with said receiver for discharging the strong liquor content thereof into said generator, means between said receiver and said absorber for preventing any fiow of fluid from said receiver to said absorber during the discharge of said strong liquor from said receiver, said means for increasing the pressure within said receiver being adapted to simultaneously heat said generator.

11. An apparatus for refrigeration comprising a generator and an absorber having a receiver connected therebetween, the latter to be filled with strong liquor from said absorber, continuously operative means for heating a portion of said receiver for increasing the pressure of said receiver whereby the strong liquor content thereof is discharged into said generator, means for preventing said strong liquor from coming in contact with said portion of said receiver until said receiver is substantially filled with strong liquor, and means independent of said absorber for decreasing the fluid pressure in said receiver.

12. An apparatus for refrigeration comprising a generator and an absorber having a receiver connected therebetween, the latter to be filled with strong liquor from said absorber, means for heating a portion of said receiver for increasing the pressure of said receiver whereby the strong liquor content thereof is discharged into said generator, means for preventing said strong liquor from coming in contact with said portion of said receiver until said receiver is substantially filled with strong liquor, and means for supplying weak liquor from said generator to said receiver for absorbing the vaporous content thereof.

13. An apparatus for refrigeration comprising connected therebetween, the latter to be filled with strong liquor from said absorber, means for heating a portion of said receiver for increasing the pressure of said receiver whereby the strong liquor content thereof is discharged into said generator, means for preventing said strong liquor from coming in contact with said portion of said receiver until said receiver is substantially filled with strong liquor, and an unobstructed two-way passage of restricted cross section between said generator and the bottom of said absorber for continuously supplying a metered quantity of weak liquor from said generator to said absorber.

14. An apparatus for refrigeration comprising a generator, an absorber, and means for transferring strong liquor from said absorber to said generator, said transferring means comprising a receiver connected to said absorber for receiving strong liquor therefrom, a connection between said receiver and said generator for delivering strong liquor thereto, heating means for increasing the pressure in said receiver so as to force strong liquor into said generator, and means for reducing the pressure in said receiver below that of said absorber so as to permit the delivery of strong liquor from said absorber to said receiver, said last-mentioned means comprising means for delivering weak liquor to said receiver.

15. In an absorption system oi. the two pressure type, a generator, a continuously operative heating element therefor, an absorber, and means for transferring strong liquor from said absorber to said generator, said means comprising a receiver connected to said absorber for receiving strong liquor therefrom, a coil connected to said receiver so as to be supplied with strong liquor therefrom, said coil being heated by said heating element and being operable for effecting the transfer of strong liquor from said receiver to said generator and means for reducing the pressure in said receiver so as to permit the delivery of strong liquor from said absorber to said receiver.

16. In an absorption system of the two pres-- sure type, a generator, a continuously operative heating element therefor, an absorber, a receiver connected to said absorber for receiving strong liquor therefrom, means for reducing the pressure in said receiver so as to permit the transfer of strong liquor from said absorber to said receiver, and means including a thermosiphon coil connected to said receiver so as to receive strong liquor therefrom and adapted to be heated by said heating element for effecting the transfer of strong liquor from said receiver to said generator.

17. In an absorption refrigerating system of the two pressure type and having an absorber and a generator, the method of transferring strong liquor from the absorber into the generator which comprises removing a quantity of strong liquor from said absorber and collecting such quantity in a receiver, heating a relatively small portion of said quantity of strong liquor for forcing the same into the generator and supplying weak liquor from said generator to said receiver for periodically reducing the pressure therein below that of said absorber.

EARL F. HUBACKER 

